There are many methods by which sellers can sale their products and/or services. One typical method is when sellers advertise a predetermined price for a product/service, and customers pay the advertized price to receive the product/service. Another typical method is when sellers may accept conditional purchase offers (CPOs) from buyers. In some cases, a typical CPO may involve specifying a price that the buyer is willing to pay for the product/service. If a seller accepts the CPO, then that seller gets paid. Even if the buyer later reneges, in some CPOs, there is a payment guarantee that the seller receives appropriate compensation, typically either the full offer price or a predetermined penalty payment. For example, typically, in some CPOs, specific details of a product/service (e.g., Hotel Name and/or specific Room Type, Airline and/or Flight Number etc) are unknown. In some instances, products/service represent excess of perishable inventory such as seats on airline flights or hotel rooms. For example, the marginal cost to an airline of selling an additional seat is extremely low. Accordingly, it can be profitable to sell a seat for a low, buyer-specified offer price, especially if the chance of otherwise selling the seat is small (e.g. soon before the flight departs).